The first copule of battery replacements of mine ended up on the floor. It's hard to figure how exactly must one lock the battery compartment so it won't pop open, but once you get it right, it does stay closed.

Still, I'd watch out for my fingers not to accidentally press the compartment (press it the right way, i mean) when holding the camera in strange (probably akward and uncomfortable) manners.

I've heard a few owners complaining about it. But, in my experience, it DOES close correctly once u get the idea of how u're supposed to do it. The strange thing is that Fuji came up with a design where, besides learning how to use the camera menus and features, one must learn to shut a lock correctly (do we want to spend time learning that?).